Automated testing equipment (ATE) is used to test a circuit board during the manufacturing process. A circuit board to be tested is placed on the ATE such that a plurality of conducting pins of the ATE, referred to generally as a "bed of nails", are brought into contact with selected portion of etch or selected terminals of the various devices mounted on the circuit board. Electrical signals are applied to various ones of the pins in electrical contact with various ones of the devices and the resulting signals from those devices are monitored at other locations by various other pins. In this manner, the effect of a known signal applied by the ATE to a device or group of devices can be compared to the expected effect. If the device or group of devices fails to respond in the expected manner, a defect is indicated.
In addition to ATE component testing, environmental testing in which the circuit board is operated at its voltage limits while at its temperature limits may be performed during the manufacturing process. Circuit boards which fail to perform as expected while at parameter limits permitted by their design specifications must also be reworked or classified accordingly.
In addition to testing during manufacture, complex circuit boards, such as disk controllers, include a microprocessor which not only executes a program to provide the desired functionality, but also executes diagnostic routines stored in ROM on the circuit board to test the functionality of the circuit board during system initialization, once the circuit board has been installed in an operational computer system. Thus, for example, a microprocessor on a disk controller board performs the function of controlling a disk and also performs diagnostic tests to test the functionality of the controller board itself and the functionality of the disks which are attached to the controller board.
When a board is diagnosed as defective by the ATE component testing, the on board diagnostic testing, or any of other tests which are performed during and subsequent to the manufacturing process, the circuit board is either rejected or reworked. When a circuit board is reworked, the circuit board along with all its test results are brought to technicians who review the test results and determine the cause of the problem. The problems associated with this process are many fold. It is desirable, for example, to execute the on board diagnostics prior to the final assembly of the system to avoid the expense of assembling a system with defective circuit boards. Further, maintaining a paper history of the circuit board provides a logistical problem. Finally, it is desirable to maintain a record of each circuit board even once the circuit board has been delivered to a customer so that statistical information as well as information on problems experienced by the customer can be examined.
It is therefore desirable to have a testing system that will permit the execution of on board diagnostics during board manufacture while maintaining a historical record of the significant diagnostic events on the circuit board itself.